It is common to seal a bottle, jar, or other container with a screw cap and a secondary sealing member across the mouth of the container. Typically, this secondary sealing member can provide evidence of tampering, a vapor barrier or, in some cases, a hermetic seal. In some cases, these secondary sealing members can be provided as a two-piece sealing member with a lower sealing portion and an upper liner portion.
A variety of two-piece sealing members have been developed and have application in the closure industry for use with a screw cap. The cap provides a reclosable closure after the sealing member has been removed by a consumer to gain access to the contents of the container. Often the lower sealing portion includes a heat sensitive sealing layer or bonding layer covered by a metal foil layer. The heat sensitive bonding layer adheres the sealing member to the rim or mouth of a container. The upper liner portion of the sealing member includes a compressing agent (e.g., pulp board, synthetic foam, or the like) that is adjacent the interior of the screw cap and at the opposite end of the sealing member from the heat sensitive sealing layer. There is also generally a release layer, such as a wax layer, adjacent the compressing agent and between the upper liner portion and the lower sealing portion. The release layer is effective to initially hold the upper liner portion to the lower sealing portion to form a unitary or one-piece structure, but the release layer permits the sealing member to separate between these two portions upon cap removal.
In use, the sealing member is inserted into a container or bottle cap at a closure manufacturer as the single or unitary structure where the release layer holds the upper liner portion to the lower sealing portion. The cap generally includes internal threading or other internal retention projections that hold the sealing member against the upper surface of the cap by friction or interference. The cap and sealing member combination may then be provided to an end user that places the cap onto a container mouth where the sealing member is induction sealed to the upper rim of a bottle or container. During induction sealing, an electromagnetic field generated by induction heating equipment heats the metal foil layer in the lower sealing portion to activate the heat sensitive sealing layer for bonding to the rim or mouth of a container. At the same time, the induction heating also causes the release layer to separate the upper liner portion from the lower sealing portion. In the case of the wax layer, the induction heating causes the wax to melt and be absorbed by the compressing agent in the upper liner portion. This converts the one-piece sealing member into two pieces, with the heat sensitive sealing layer bonding the lower sealing portion to the container rim, and the melted wax being absorbed by the compressing agent in the upper liner portion. The compressing agent generally remains lodged in the inner portion of the cap as a cap liner, and the lower sealing member remains adhered to the container when the cap is removed from the bottle by the consumer.
When the cap is removed, the consumer must tear, penetrate, break, or remove the lower sealing portion of the sealing member before the contents of the container may be accessed. The cap may then be screwed back into place on the container neck. Upon removal of the cap, a missing or damaged sealing member can alert the consumer that the contents of the container may have been tampered with prior to purchase.
It is increasingly common to also include an anti-counterfeiting measure along with such sealing members. For instance, such a sealing member can be provided with an optical security feature, such as a hologram, that is visible to the purchaser after the cap is removed. The pattern of the hologram or other optical security feature may be a unique identifier of a particular manufacturer.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the disclosure.